Method and apparatus for cleaning substrates

Abstract

An ultrasonic vibrating apparatus and an ultrasonic cleaning apparatus capable of permitting ultrasonic cleaning of a wafer to be carried out using an existing cleaning tank and while keeping the object immersed in cleaning liquid. An ultrasonic wave is irradiated to a cleaned object while keeping it immersed in cleaning liquid stored in a cleaning tank formed with an upper opening. A vibrating plate is securely mounted thereon with an ultrasonic transducer through a wave transmission element and arranged so as to close the upper opening of the cleaning tank in a cover-like manner. The vibrating plate is so arranged that a vibrating surface thereof downwardly faces and is immersed in the cleaning liquid.

What is claimed is:  
     
         1 . A method for treating objects, the method comprising: 
 applying a plurality of acoustic waves from an energy source to an upper portion of an object to be treated, the object being immersed in fluid, the fluid comprising liquid; and    maintaining the acoustic waves from the upper portion of the object to a lower portion of the object such that the entire object is subjected to the acoustic waves, the object being substantially free from a shadowing influences for an other object in the fluid.    
     
     
         2 . The method of  claim 1  wherein the acoustic waves comprise a frequency ranging from about 200 kHz to 5 Mhz.  
     
     
         3 . The method of  claim 1  wherein the fluid comprises water and ammonium ions.  
     
     
         4 . The method of  claim 1  wherein the fluid comprises an etchant, the etchant being selected from HF, HCl, and H 2 SO 4 .  
     
     
         5 . The method of  claim 1  wherein the acoustic waves prevent a particle from reattaching itself onto a surface of the object, the particle having a dimension of less than 0.5 micron in size.  
     
     
         6 . The method of  claim 1  further comprising directing fluid across a plate coupled to the energy source to generate a force that maintains the plate free from a possibility of accumulating a bubble.  
     
     
         7 . The method of  claim 6  wherein the force is a flow.  
     
     
         8 . The method of  claim 1  wherein the object is selected from a semiconductor wafer or a flat panel, a mask, a disk, or a MEMS object.  
     
     
         9 . The method of  claim 8  wherein the semiconductor wafer is selected from a patterned wafer or a blank wafer.  
     
     
         10 . A system for treating objects, the system comprising: 
 a vessel configured for holding a fluid comparing a liquid, the vessel comprising a lower portion and an upper portion;    an acoustic vibrational source being configured to operate at 400 kHz to 5 MHz, the acoustic vibrational source being coupled to the upper portion of the vessel, the acoustic vibrational source having an active area that is substantially similar to a width of a substrate being treated, the active area providing acoustic waves along an entire width of the substrate being treated.    
     
     
         11 . The system of  claim 10  wherein the acoustic vibrational source is mounted on a lid of the vessel.  
     
     
         12 . The system of  claim 10  wherein the vessel is manufactured from quartz.  
     
     
         13 . The system of  claim 10  wherein the acoustic vibrational source comprises a plurality of transducers, each of the transducers being capable of converting an electrical signal into a mechanical signal.  
     
     
         14 . The system of  claim 10  wherein the lower portion of the vessel is formed to conform to a bottom region of the substrate to be treated.  
     
     
         15 . The system of  claim 10  wherein the acoustic vibrational source comprises a plurality of transducers, each of the transducers being capable of converting an electrical signal into a mechanical signal through a plate, a portion of the plate being submerged in the liquid.  
     
     
         16 . The system of  claim 10  wherein the acoustic vibrational source is sealed in a chamber, the chamber being maintained in an inert atmosphere.  
     
     
         17 . The system of  claim 10  wherein the acoustic vibrational source is maintained under a positive pressure relative to an ambient pressure.  
     
     
         18 . The system of  claim 10  wherein the acoustic vibrational source is mounted on a movable lid of the vessel.  
     
     
         19 . The system of  claim 10  wherein the vessel comprises at least one sensor for detecting the fluid level such that a plate coupled to the acoustic vibrational source is maintained in the fluid.  
     
     
         20 . An ultrasonic vibrating apparatus for irradiating an ultrasonic wave to an object kept immersed in cleaning liquid stored in a cleaning tank formed with an upper opening, comprising: 
 a vibrating plate for closing said upper opening of said cleaning tank in a lid-like manner; and    at least one ultrasonic transducer fixedly mounted on said vibrating plate;    said vibrating plate being arranged in such a manner that a vibrating surface thereof outwardly faces and is adapted to be immersed in the cleaning liquid stored in said cleaning tank.    
     
     
         21 . An ultrasonic vibrating apparatus for irradiating an ultrasonic wave to an object kept immersed in cleaning liquid stored in a cleaning tank formed with an upper opening comprising: 
 a vibrating plate for closing said upper opening of said cleaning tank in a lid-like manner;    a wave transmission element;    at least one ultrasonic transducer fixedly mounted on said vibrating plate through said wave transmission element; and    said vibrating plate being arranged in such a manner that a vibrating surface thereof outwardly faces and is adapted to be immersed in the cleaning liquid stored in said cleaning tank.    
     
     
         22 . An ultrasonic vibrating apparatus as defined in  claim 20  or  21 , wherein said vibrating plate is provided with a hinge and/or a vertically moving means, to thereby be operatively associated with said cleaning tank.  
     
     
         23 . An ultrasonic vibrating apparatus as defined in any one of  claims 20  to  22 , wherein a vibrational frequency of said vibrating plate is set to be within a range of between 200 kHz and 5 MHz.  
     
     
         24 . An ultrasonic vibrating apparatus as defined in any one of  claims 20  to  23 , wherein said vibrating plate is made of a material subjected to a treatment selected from fluoroplastic coating and passivation; said material being selected from the group consisting of stainless steel such as SUS 304, SUS 316 or SUS 316L; tantalum; fused quartz; silicon carbide; and stainless steel of 1 μm (Rmax) in surface roughness.  
     
     
         25 . An ultrasonic vibrating apparatus as defined in any one of  claims 20  to  24 , .further comprising a bubble removing means arranged on a lower surface of said vibrating plate so as to eject cleaning liquid of a composition identical to that of the cleaning liquid in said cleaning tank to remove bubbles adhering to the lower surface of said vibrating plate therefrom.  
     
     
         26 . An ultrasonic cleaning apparatus comprising: 
 the ultrasonic vibrating apparatus defined in any one of  claims 20  to  25 ; and    a cleaning tank formed with an upper opening on which said ultrasonic vibrating apparatus is mounted.    
     
     
         27 . An ultrasonic cleaning apparatus comprising: 
 the ultrasonic vibrating apparatus defined in any one of  claims 20  to  25 ;    a cleaning tank formed with an upper opening on which said ultrasonic vibrating apparatus is mounted; and    a bubble removing means arranged in proximity to said upper opening of said cleaning tank and constructed so as to eject cleaning liquid of a composition identical to that of cleaning liquid stored in said cleaning tank to a lower surface of said vibrating plate of said ultrasonic vibrating apparatus, to thereby remove bubbles adhering to said lower surface of said vibrating plate therefrom.